Four diff erent samples of pure scheelite α-Bi 2 Mo 3 O 12 were synthesized by the fast microwave-assisted hydrothermal method.

By adjusting the pH in the preparation process, the morphologies and structures of the synthesized catalysts were changed.

TG, XRD, SEM, TEM, BET, and XPS analyses were used to investigate the characteristics of the catalyst. The sample of

α-Bi 2 Mo 3 O 12 was prepared at a calcination temperature of 500 °C and pH = 1 had the highest specifi c surface area propylene

selective oxidation properties. The conversion of propylene was 28.3% and the selectivity of acrolein was 86.4%. Compared

with α-Bi 2 Mo 3 O 12 prepared by co-precipitation and normal hydrothermal method, α-Bi 2 Mo 3 O 12 prepared by microwave

hydrothermal method has higher propylene oxidizing activity. The conversion of propylene is negatively correlated with the

crystallinity of the catalyst. This is due to the fact that higher crystallinity inhibits the lattice oxygen fl ow between the lattices,

thus inhibiting the selective oxidation and reducing the conversion of the reaction. The oxygen mobility of α-Bi 2 Mo 3 O 12

samples was characterized by XPS. The results showed that the conversion of propylene of α-Bi 2 Mo 3 O 12 were positively

correlated with its oxygen mobility strength. A probable mechanism for the selective oxidation of propylene was proposed.

This work not only off ers a high-effi ciency method for the rapid preparation of bismuth molybdate catalysts but also extends

the application of microwave-assisted hydrothermal synthesis in the fi eld of selective oxidation of propylene.